JPH10121072A - Nonsmoking briquette made of low-grade coal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain nonsmoking briquettes prevented from forming sooty smoke in the initial stage of burning and markedly suppressed in the formation of sulfur dioxide gas during burning by forming them from the main body comprising a low-grade coal, a sulfur fixing agent, etc., and an igniter. SOLUTION: Examples of the low-grade coals (A) include subbituminous coal and lignite specified in the classification of coal according to JIS M1002, and their calorific values are 7,300-7,800kcal/kg and 5,800-7,300kcal/g, on the basis of anhydrous inorganic mineral, respectively, and their fuel ratios (fixed carbon/volatile) are below 1.5 or below, respectively. Examples of the sulfur fixing agents (B) used include slaked lime, soda ash and potassium carbonate. 100 pts.wt. component A is mixed with 1-10 pts.wt. component B and a clay mineral comprising silica, alumina or iron oxide to form a main body. This body is surrounded with an igniter comprising 100 pts.wt. charcoal, 1-10 pts.wt. component B and 1-15 pts.wt. binder. These components are mixed with each other so that the melting point of the residual ash of the main body may be 1,100-1,400 deg.C and that the rate of ash left after burning may be 25-35%, and the obtained mixture is molded into a desired shape and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a smokeless briquette made of low-grade coal such as subbituminous coal and lignite coal.

[0002]

2. Description of the Related Art Low-grade coal has a higher volatile content than anthracite, and when it is used as it is in the form of briquettes such as briquettes, a large amount of soot is generated during combustion, particularly at the beginning of combustion. have. Furthermore, when the sulfur content is high, there is a problem that a large amount of harmful sulfur dioxide gas is generated during combustion. In order to solve the problem during the generation of soot, there is a method in which waste wood powder is blended with coal to form the coal, or the coal is carbonized in advance and then molded.
For example, JP-A-57-78492 discloses that the composition ratio (weight) of powdery non-caking subbituminous coal or caking bituminous coal and waste wood powder is 9: 1 to 5: 5. Is disclosed. Further, in order to solve the problem of the sulfur dioxide gas generation, coal is mixed with a binder and a sulfur fixing agent such as lime, slaked lime and soda ash, and molded. For example, JP-A-63-1
Japanese Patent No. 37994 discloses a method of producing molded charcoal by blending lime as a sulfur fixing agent and cement as a binder with pulverized low-grade coal powder, molding the blend into a desired shape, and drying the molded product. A method for doing so is disclosed. JP-A-62-135594 discloses a molded coal comprising anthracite, slaked lime or ash, soil such as bentonite or clay, and a binder such as methylcellulose. However, this publication does not only describe low-grade coal, but also does not describe what action the soil such as the bentonite or clay has. On the other hand, the present applicant has proposed a molded coal comprising low-grade coal, a clay mineral, a sulfur fixing agent and a binder in Japanese Patent Application Laid-Open No. Hei 7-310084. However, when used as briquettes, there is a problem that desired quality cannot be obtained depending on the composition of the raw materials.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to mix a low-grade coal with a sulfur-fixing agent or a clay mineral as a main body to reduce the residual ash ratio of briquettes after combustion by 25 to 35%. In addition, by providing an igniting agent in the upper portion of the briquette main body, the generation of soot in the initial stage of combustion is suppressed to a level that does not pose a practical problem. Another object of the present invention is to significantly suppress the generation of sulfur dioxide during combustion by blending a sulfur fixing agent into a briquette main body and an ignition agent.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to provide a main body made of low-grade coal and a sulfur fixing agent, or a clay mineral, and a charcoal, a sulfur fixing agent provided on the main body. It is achieved by briquettes comprising two layers of an igniting agent comprising a binder, having a melting point of ash in the main body of 1100 to 1400 ° C, and having a residual ash ratio of 25 to 35% after combustion.

[0005] Specific examples of the low-grade coal of the main body in the present invention include sub-bituminous coal (E) and lignite (F) in the carbon classification according to JIS M1002. The calorific value of these low-rank coals is 7300
kcal / kg or more and less than 7800 kcal / kg, and lignite is 5800 kcal / kg or more and 7300 kc
a1 / kg. The fuel ratio (fixed carbon / volatile content) of these low-rank coals is less than 1.5. Specific examples of the sulfur fixing agent to be mixed in the main body and the ignition agent in the present invention include known sulfur fixing agents such as slaked lime, soda ash, potassium carbonate, and iron oxide. It is preferable to use slaked lime and soda ash or potassium carbonate in combination in order to effectively fix the sulfur content in the briquette during the burning of the briquette.

Further, as a specific example of the charcoal of the igniting agent, a charcoal having a calorific value of 7000 kcal / kg or more based on anhydrous and mineral-free substances is preferable. Specific examples of the binder include known binders such as pulp waste liquor, pitch, cement, starch, methyl cellulose, carboxymethyl cellulose, bentonite, and polyvinyl alcohol.

In the present invention, the amount of the sulfur fixing agent in the main body is 1 to 10 parts by weight per 100 parts by weight of low-grade coal,
The compounding amount of the sulfur fixing agent of the ignition agent is preferably 1 to 10 parts by weight per 100 parts by weight of charcoal. In the present invention, if the compounding amount of the sulfur fixing agent is too small, the fixation ratio of sulfur contained in briquettes during combustion becomes low, and it is not possible to sufficiently suppress the generation of sulfurous acid gas. Even if the blending amount of the sulfur fixing agent is excessively large, there is no difference in the effect of suppressing sulfurous acid gas during combustion, and the calorific value of briquettes is reduced.

The amount of the binder to be mixed with the igniting agent is 1 charcoal.
1 to 15 parts by weight per 00 parts by weight is preferred. If the amount of the binder in the igniting agent is too small, the strength is low and a problem occurs in handling. On the other hand, if the amount of the binder is excessively increased, the strength is improved, but the ignitability is reduced, and the production cost is increased. In the present invention, a binder may be added to the main body as needed.

In the present invention, the amount of the igniting agent is preferably 5 to 15 parts by weight per 100 parts by weight of the main body. If the amount of the igniting agent is excessively small, the effect of suppressing the generation of smoke and the generation of sulfurous acid gas at the time of combustion of briquette decreases,
Further, the ignitability also decreases. On the other hand, even if the blending amount is excessively large, there is no difference between the effect of suppressing the generation of smoke and the effect of suppressing the generation of sulfur dioxide.

In the present invention, the ash ratio after burning of the briquette is adjusted to be 25 to 35%. The term "residual ash ratio" used in the present invention is defined as follows. Residual ash ratio (%) = (Amount of residual ash after combustion (g) / weight of briquettes before combustion (g)) × 100 Ash content of briquettes prepared so that the residual ash ratio after combustion is 25 to 35% Has the effect of suppressing the generation of soot generated in the early stage of the combustion of briquettes. In addition, this ash, when used in combination with a known sulfur fixing agent, significantly suppresses the generation of sulfur dioxide gas when briquettes are burned, in other words, significantly suppresses the decomposition of, for example, sulfur fixed as gypsum. It has the effect of doing. When the residual ash ratio of briquettes is less than 25%,
The effect of suppressing the generation of soot and the generation of sulfurous acid gas during the combustion of briquettes is reduced, and furthermore, the shelves are dropped during combustion, leading to deterioration of the combustion state. On the other hand, if the residual ash ratio is more than 35%, no difference is observed between the effect of suppressing the generation of soot and the effect of suppressing the generation of sulfurous acid gas, and the calorific value of the briquette decreases, which is not preferable.

When the content of non-mineral substances such as ash and sulfur fixing agent in coal is small, the residual ash ratio after combustion is 2%.
It is desirable to add a clay mineral to the main body so that the content becomes 5 to 35%. The clay mineral to be added is a natural mineral mainly composed of silica, alumina and iron oxide. For example, on an anhydrous basis, SiO ₂ : 60 to
70% by weight, Al ₂ O ₃ : 15 to 25% by weight, Fe ₂ O ₃ =
Examples of the clay mineral include 5 to 10% by weight and MgO = 1 to 2% by weight.

In addition, when the clay mineral is blended in the main body, the melting point of the residual ash is 1100 to 1400 so that the residual ash can be maintained in a state close to the initial briquette shape when used as briquette. The composition is blended so that the temperature becomes ℃. On the other hand, the residual ash ratio of the ignition agent is preferably set to 2 to 10%.
If the residual ash ratio of the igniting agent is less than 2%, the effect of suppressing soot generation and the effect of suppressing sulfur dioxide gas are low. If the residual ash ratio is more than 10%, the effect of suppressing soot and sulfur dioxide gas is suppressed. Is not recognized and the ignitability deteriorates.

[0013] The briquette of the present invention comprises a main body made of low-grade coal and a sulfur fixing agent, or a clay mineral;
It can be manufactured by molding an ignition agent composed of a sulfur fixing agent and a binder into a desired shape and then drying it. At the time of molding, a plurality of ventilation holes penetrating in the vertical direction were provided at the center and the periphery of the briquette, and the opening ratio was 11 to 1.
Preferably, it is 6%. When the porosity is smaller than 11%, the ignitability, the smoke suppression effect, and the sulfur dioxide gas generation suppression effect are reduced. On the other hand, even if the porosity is larger than 16%, there is no difference in the effect of suppressing the generation of soot and the effect of suppressing the generation of sulfurous acid gas, the strength is further reduced, and problems arise in handling.

[0014]

According to the present invention, the residual ash ratio after burning of briquette is adjusted to 25 to 35% by blending a sulfur fixing agent or a clay mineral with low-grade coal as the main body, Further, by providing the igniting agent on the upper portion of the briquette main body, the generation of soot in the initial stage of combustion can be suppressed to a practically acceptable level. Further, by adding the sulfur fixing agent not only to the briquette main body but also to the igniting agent, it is possible to significantly suppress the generation of sulfurous acid gas during combustion.

[0015]

EXAMPLES Examples and comparative examples are shown below. In the following description, “parts” means “parts by weight”. The analytical values of the two low-grade coals used in the examples and comparative examples are shown below. Low-grade coal A Low-grade coal B Moisture 20.7% Moisture 17.7% Ash 32.4% Ash 1.4% Volatile 37.1% Volatile 39.1% Fixed carbon 9.8% Fixed carbon 41. 8% Fuel ratio 0.26 Fuel ratio 1.07 Heat value 2720 kcal / kg Heat value 5960 kcal 1 / kg Total sulfur 5.68% Total sulfur 0.11%

The analysis values of the charcoal used in the examples and comparative examples are shown below. Moisture 4.6% Ash 1.4% Volatile 28.9% Fixed carbon 65.1% Heat value 6860 kcal / kg Total sulfur 0.04%

The analytical values of the clay mineral used in Examples 2 and 3 are shown below. SiO ₂ 65.2% Al ₂ O ₃ 19.3% Fe ₂ O ₃ 7.2% MgO 1.7% CaO 0.8%

The melting characteristic temperature of ash is measured according to JIS M8801.
Perform according to. The sulfur fixation ratio (R: unit%) is a value determined by the following equation. R = S _a × S _a in 100 / S ₀ formula is the total amount of sulfur in briquettes combustion ash, S ₀ is the total amount of sulfur briquettes.

Example 1 A predetermined amount of water was added to 100 parts of low-grade coal A powder and 4 parts of slaked lime as a briquette main body, and the mixture was sufficiently kneaded. Charcoal powder 100 parts, slaked lime 5 parts, bentonite 1 as ignition agent
A predetermined amount of water was added to 0 parts and 1 part of polyvinyl alcohol, and kneaded sufficiently. Next, a two-layered briquette was produced by pressure molding at a ratio of 10 parts of the igniting agent to 100 parts of the main body. The residual ash ratio of the molded briquette was adjusted to 30%. The molded briquette had 16 ventilation holes penetrating vertically, and the opening ratio was 12%. The briquettes thus obtained were placed on a gas stove, and the igniting agent was heated for 2 minutes and then burned with the briquettes. A little amount of soot was observed at the beginning of combustion, and the sulfur fixation rate was 83%. The melting point of the residual ash was 1340 ° C.

Example 2 100 parts of low-grade coal B powder, slaked lime 4
, 35 parts of clay mineral, and 2 parts of soda ash, a predetermined amount of water was added and sufficiently kneaded. A predetermined amount of water was added to 100 parts of charcoal powder, 5 parts of slaked lime, 10 parts of bentonite, and 1 part of polyvinyl alcohol as an igniting agent, followed by sufficient kneading. Next, a two-layered briquette was manufactured by pressure molding at a ratio of 10 parts of the igniting agent to 100 parts of the main body. Example 1 was repeated except that the residual ash ratio of the molded briquettes was adjusted to 30%. Some smoke was observed in the early stage of combustion, and the sulfur fixation rate was 80%. The melting point of the residual ash was 1240 ° C.

Example 3 100 parts of low-grade coal A powder, slaked lime 4
A predetermined amount of water was added to 1 part, 2 parts of clay mineral, 2 parts of soda ash, and 1 part of potassium carbonate, and kneaded sufficiently. A predetermined amount of water was added to 100 parts of charcoal powder, 5 parts of slaked lime, 10 parts of bentonite, and 1 part of polyvinyl alcohol as an igniting agent, followed by sufficient kneading. Next, a two-layered briquette was produced by pressure molding at a ratio of 10 parts of the igniting agent to 100 parts of the main body. Example 1 was repeated except that the residual ash ratio of the molded briquette was adjusted to 34%. No smoke was observed from the beginning to the end of combustion, and the sulfur fixation rate was 99%. The melting point of the residual ash was 1310 ° C.

Comparative Example 1 Example 1 was repeated except that no ignition agent was provided. A considerable amount of smoke was observed from the beginning of combustion, and the sulfur fixation rate was 4
5%.

Comparative Example 2 100 parts of low-grade coal B powder and slaked lime 4
, 10 parts of clay mineral, 2 parts of soda ash, and 1 part of potassium carbonate, a predetermined amount of water was added and kneaded well. A predetermined amount of water was added to 100 parts of charcoal powder, 5 parts of slaked lime, 10 parts of bentonite, and 1 part of polyvinyl alcohol as an igniting agent, followed by sufficient kneading. Next, a two-layered briquette was produced by pressure molding at a ratio of 10 parts of the igniting agent to 100 parts of the main body. Example 1 was repeated except that the residual ash ratio of the molded briquette was adjusted to 15%. A large amount of smoke was observed from the beginning to the end of combustion, and the sulfur fixation rate was 50%.

Comparative Example 3 Example 1 was repeated except that slaked lime was not added to the ignition agent. Some smoke was observed in the early stage of combustion, and the sulfur fixation rate was 62%.

Comparative Example 4 Example 2 was repeated except that the clay mineral having the following composition was used. Since the composition of the clay mineral was different and the melting point of the residual ash was 1050 ° C., the shape was deformed during the combustion test of the briquettes, the thermal power was reduced, and a good combustion state could not be maintained. Analysis of clay mineral _{SiO 2 62.0% Al 2 O 3} 11.2% Fe 2 O 3 9.3% MgO 2.7% CaO 10.5%

Claims (6)

[Claims] 1. A main part made of a low-grade coal and a sulfur fixing agent, or a clay mineral, and an ignition agent made of charcoal, a sulfur fixing agent and a binder provided on the main part, and The melting point of the ash in the main body is 1100-1400 ° C
A low-grade coal smokeless briquette characterized by having a residual ash ratio of 25 to 35% after combustion. 2. The low-grade coal smokeless briquette according to claim 1, wherein the main body has 1 to 10 parts by weight of the sulfur fixing agent based on 100 parts by weight of the low-grade coal. 3. The low-grade coal-free smokeless briquette according to claim 1, wherein the igniting agent is 1 to 10 parts by weight of a sulfur fixing agent and 1 to 15 parts by weight of a binder with respect to 100 parts by weight of charcoal. 4. An igniting agent is used in an amount of 5 parts per 100 parts by weight of the main body.
The low-grade coal smokeless briquette according to claim 1, wherein the amount is from 15 to 15 parts by weight. 5. The low-grade coal has a calorific value of 7300 kcal / kg or more and 7800 kcal / k based on anhydrous mineral-free substances.
g of subbituminous coal, or 5800 kcal / kg or more,
2. The low-grade coal-free smokeless briquette according to claim 1, wherein the coal is lignite having a fuel ratio (fixed carbon / volatile matter) of less than 7,300 kcal / kg and a fuel ratio of less than 1.5. 6. A plurality of ventilation holes penetrating vertically in the center and around the center of the briquette, and the opening ratio thereof is l.
The low-grade coal smokeless briquette according to claim 1, which is 1 to 16%.